Xinhua News Agency, Beijing, February 16 (Reporter Zhang Quan, Wang Ying) The reporter learned from the Chinese Academy of Sciences on the 16th that Chinese scientists used the Dalian coherent light source to discover the first case of a roaming reaction channel with a high excited state of molecules, indicating that roaming reactions are common in chemical reactions and provide a new perspective for understanding and chemical reactions.
The research was jointly completed by the experimental team of Prof. Yuan Kaijun and Academician Yang Xueming of Dalian Institute of Chemical Physics, Chinese Academy of Sciences, and the theoretical team of Prof. Fu Bina and Academician Zhang Donghui, and the relevant results have been published in the international academic journal Science.
The roaming mechanism is a novel reaction mechanism that is different from the traditional transition state theory. Fu Bina introduced that in chemical reactions, molecules and atoms need to climb the "mountain" of energy barriers like "mountaineers" in order to be converted into new substances. In the traditional theory, chemical reactions mainly follow the path of minimum energy, but some chemical reaction processes may "go around", and atoms or groups "roam" near and far near molecules, and finally form products that are different from traditional chemical reactions, which is called roaming reactions.
At the beginning of the 21st century, scientists first discovered the roaming reaction. Since then, the analysis of the roaming reaction mechanism has been limited to the low-electron state and ground state of the molecule, and the existence of the roaming reaction when the molecule reaches the high-excited state has not been confirmed.
Molecules can only reach the highly excited state after absorbing high-energy photons of extreme ultraviolet light, and high-brightness, tunable extreme ultraviolet light sources are very lacking. Yuan Kaijun said that the Dalian coherent light source solves this problem, and its output of high-brightness, wavelength-tunable extreme ultraviolet light can excite any molecule to a specific high-excited state.
In this study, the experimental team prepared a highly excited sulfur dioxide molecule using a Dalian coherent light source, and combined with the self-developed high-resolution ion imaging technology to detect the quantum state distribution of excited oxygen products. The theoretical team used the self-developed method of constructing high-precision excitation potential energy surface and the kinetic calculation of quantum state resolution of products to accurately reproduce the observed phenomena in the experiment, indicating that roaming reactions are ubiquitous in chemical reactions.
Through this research, we have gained a new understanding of the previous theories of chemical reactions, and many phenomena that cannot be explained by traditional chemical reaction theories may be explained by the roaming reaction mechanism. This will further advance the understanding of the nature of chemical reactions. Academician Yang Xueming said. (ENDS).